Macromolecule Match-Up
Which macromolecule makes up most of the cell membrane structure?
What are lipids (phospholipids)?
What is the main job of the cell membrane?
(what is it called when it is selective?)
To control what enters and leaves the cell (selectively permeable).
Moving molecules from high to low concentration without energy is called…
What is diffusion (simple transport)?
Osmosis is the diffusion of what substance?
Water
Sports drinks often contain electrolytes. Why are they better than plain water after heavy sweating?
They replace lost ions and maintain osmotic balance.
Which macromolecule helps transport substances across the membrane?
What are proteins?
Why are the phospholipid tails hydrophobic while the heads are hydrophilic?
Tails are nonpolar (repel water), heads are polar (attract water).
Which transport process requires ATP?
What is active transport?
In a hypertonic solution, will a cell shrink or swell?
It will shrink.
Why are IV solutions given as saline instead of pure water?
To avoid bursting red blood cells (maintain isotonic conditions).
Cholesterol in the membrane is an example of which macromolecule, and what is its role?
What are lipids; they stabilize fluidity of the membrane.
Which part of the membrane is responsible for cell signaling?
Receptor proteins.
Give one example of facilitated diffusion in cells.
Glucose (or a large molecule) moving through a protein channel (high to low concentration).
A plant wilts after not being watered. Explain using osmosis.
Water left the plant cells in a hypertonic environment, causing plasmolysis.
Salt is spread on icy roads. How could this harm plants nearby?
Creates a hypertonic environment, pulling water out of plant roots.
Explain how carbohydrates attached to the cell membrane contribute to its function.
They act as ID tags for cell recognition and communication.
Predict what would happen if the cell membrane lost all of its proteins.
It could not transport molecules selectively or communicate properly.
Why does active transport matter if diffusion already moves molecules?
It allows cells to move substances against a concentration gradient.
Why do red blood cells burst in pure water?
Water rushes in (hypotonic), and without a cell wall, they lyse.
Cystic fibrosis is caused by a defective chloride ion channel. How does this affect transport across the membrane?
It prevents proper ion movement, leading to thick mucus buildup.
Compare the role of proteins and lipids in the membrane’s selective permeability.
Lipids form a barrier to most molecules; proteins allow specific molecules in/out.
Describe how the amphipathic nature of phospholipids creates a bilayer in water.
Hydrophilic heads face water; hydrophobic tails cluster inward.
A nerve cell pumps sodium out and potassium in at the same time. Which transport process is this?
The sodium-potassium pump (active transport).
A freshwater fish placed in saltwater dies. Explain in terms of osmosis.
Water leaves its cells into the hypertonic saltwater, causing dehydration and cell collapse.
Aquaporins are specialized protein channels. Why are they important in kidney function?
They allow rapid, controlled movement of water for balancing hydration.